This presentation of a Hasidic legend has everything a reader could want: a suspenseful story, an insightful lesson and brilliant pictures that accelerate the delivery of both. Central to the plot is the custom of tashlikh, the ritual casting of sins into the water on the first day of Rosh Hashanah. Gershon the baker, ""not always the best person he could be,"" begins to rely on this practice as a way of dealing with his mistakes: instead of apologizing and making amends, he sweeps his thoughtless deeds into the cellar every Friday and, on Rosh Hashanah, he stuffs them into a sack, drags it to the sea and tosses it in. Of course, he will learn true repentance - but not before he receives a cryptic prophecy from a sage and, much later, faces down the sea monster his sins have created. Relegating words like tashlikh to a meaty author's note (which also describes Jewish principles of t'shuvah, or repentance), Kimmel (Hershel and the Hanukkah Goblins) uses everyday language, letting the moral shine through his astute storytelling. The airy watercolor illustrations, loaded with period detail, transcend the particularities of the setting by virtue of Muth's (Come On, Rain!) expansive imaginative vision. He enhances the comedy in the premise by painting the sins as tiny horned imps who jeer as they face Gershon's broom (they grow a bit nastier as the story advances), yet he leaves room for a humane depiction of Gershon, more self-absorbed than wicked, and for a psychologically canny and dramatic portrayal of the monster. A memorable work, welcome at any time of year. Ages 5-up. (Sept.)